It is estimated that alcohol dependency affects over 10 million Americans and that the cost of alcohol related problems totals over 100 billion dollars. Alcohol consumption impairs both humoral and cell-mediated immunity. Natural killer (NK) cells play an important role in immuno- surveillance against certain infectious diseases and cancer and especially tumor metastasis. We showed previously that NK cell cytolytic activity is inhibited in the blood and spleen of mice consuming 20% w/v ethanol in the drinking water, however, NK cytolytic activity in erythrocyte-depleted splenocytes and nylon wool non adherent splenocytes is augmented by 1000 IU/ml recombinant interleukin 2 (rIL2) in vitro and by poly I:C administration in vivo. Highly enriched splenic NK cells (up to 88% purity) exhibit impaired NK cytolytic activity, but also show heightened reactivity to short-term incubation with RIL2. However, their ability to increase in number after 6 days of culture in media containing 1000 IU/ml RIL2 is impaired, and they have suppressed by lymphokine activated killer cell (LAK) activity. Paradoxically, metastasis of BL6 melanoma is inhibited in mice consuming levels of ethanol that inhibit (20% w/v) and do not affect (10% w/v) NK cell activity in tumor-free mice. The objective of this proposal is to determine the mechanism(s) underlying these findings. Three specific aims are proposed: 1) to identify the defects in cytotoxic function of highly enriched NK cells, 2) to determine if the proliferative response of highly enriched NK cells is defective, and 3) to determine the role of NK cells in the ethanol- related inhibition of tumor metastasis. We will conduct experiments to examine if target binding between NK cells and tumor cells elicits an effective signal transmission by examining the kinetics of the lytic response to calcium, and by determining NK cell recycling rate. The failure of NK cells from ethanol-consuming mice to increase in number will be examined by proliferation and cell-cycle experiments. The potential NK-independent response of ethanol consumption on metastasis of BL6 melanoma will be shown by experiments in beige mice, which are deficient in NK cells. Experiments in beige-nude mice will ascertain the contribution of T cells to the induction of the defect in NK cell cytolytic activity and to the antimetastatic activity of ethanol. Experiments will also be conducted to determine the clearance of radiolabeled BL6 cells and to determine the effect of ethanol on modulation of host cytokine factors involved in tumor metastasis.